White-winged Crossbills feed exclusively on conifer seeds extracted from pine cones. Their populations in New England vary from year to year, as they wander in search of good cone crops. Crossbills have an extremely unique bill, which is perfectly suited for extracting seeds from pine cones. This year, a phenomenal invasion of boreal finches (like the White-winged Crossbill) is underway in North America. When food crops are poor (fruit and seeds), northern birds flood into southern areas searching for greener pastures. So far this fall, Common & Hoary Redpolls, Evening & Pine Grosbeaks, and White-winged & Red Crossbills are all on the move. Other species like the Red-breasted Nuthatch and Bohemian Waxwing are on the move as well.

This certainly explains why I came across a small flock of four Pine Grosbeaks on campus here in Maine - I've never seen them before in my life, and feel very luck to have seen them! Thank you for providing this information, and for sharing your photos!